Advertisement

The European Physical Journal E

, Volume 24, Issue 1, pp 27–33 | Cite as

Electroconvection in nematics above the splay Fréedericksz transition

  • R. Stannarius
  • J. Heuer
Regular Article

Abstract.

We present a basic model for an instability leading to a novel type of electroconvection patterns observed above the splay Fréedericksz transition in nematics. Such patterns, with wave vector perpendicular to the director easy axis, are found in planar sandwich cells under crossed polarizers, they do not produce shadowgraph images at onset. An adaptation of the classical Carr Helfrich mechanism is introduced. The ground state is a tilted director field uniform in the cell plane. The proposed mechanism destabilizes this director field and leads to a structure with modulated out-of-plane (twist) deformations. Experimental confirmation is provided by polarizing microscopy. All experimental observations are qualitatively explained with the proposed model.

PACS.

05.45.-a Nonlinear dynamics and chaos 47.20.-k Flow instabilities 61.30.-v Liquid crystals 

Preview

Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.

References

  1. 1.
    R. Williams, J. Chem. Phys. 39, 384 (1963)CrossRefGoogle Scholar
  2. 2.
    E.F. Carr, J. Chem. Phys. 38, 1536 (1963).CrossRefGoogle Scholar
  3. 3.
    W. Helfrich, J. Chem. Phys. 51, 4092 (1969).CrossRefGoogle Scholar
  4. 4.
    Orsay Liquid Crystal Group, Phys. Rev. Lett. 25, 1642 (1970)CrossRefADSGoogle Scholar
  5. 5.
    E.g., L. Kramer, W. Pesch, Annu. Rev. Fluid Mech. 17, 515 (1995)CrossRefADSGoogle Scholar
  6. 6.
    A. Buka, B. Dressel, W. Otowski, K. Camara, T. Toth-Katona, L. Kramer, J. Lindau, G. Pelzl, W. Pesch, Phys. Rev. E 66, 051713 (2002).CrossRefADSGoogle Scholar
  7. 7.
    E. Kochowska, S. Németh, G. Pelzl, A. Buka, Phys. Rev. E 70, 011711 (2004).CrossRefADSGoogle Scholar
  8. 8.
    T. Tóth-Katona, A. Cauquil-Vergnes, N. Éber, Á. Buka, www.e-lc.org, 12/6 (2006).Google Scholar
  9. 9.
    D. Wiant, J.T. Gleeson, N. Éber, K. Fodor-Csorba, A. Jákli, T. Tóth-Katona, Phys. Rev. E 72, 041712 (2005).CrossRefADSGoogle Scholar
  10. 10.
    M.-G. Tamba, W. Weissflog, A. Eremin, J. Heuer, R. Stannarius, Eur. Phys. J. E 22, 85 (2007). CrossRefGoogle Scholar
  11. 11.
    L.M. Blinov, M.I. Barnik, V.T. Lazareva, A.N. Trufanov, J. Phys. (Paris) 40, C3-263 (1979)Google Scholar
  12. 12.
    M. Goscianski, L. Léger, J. Phys. (Paris) 36, C1-231 (1975).Google Scholar
  13. 13.
    F. Schneider, H. Kneppe, in Physical Properties of Liquid Crystals, edited by D. Demus (Wiley-VCH, 1998) p. 352.Google Scholar
  14. 14.
    P.G. de Gennes, The Physics of Liquid Crystals (Clarendon Press, Oxford, 1974).Google Scholar
  15. 15.
    T. Carlson, K. Skarp, Mol. Cryst. Liq. Cryst. 78, 157 (1981)CrossRefGoogle Scholar
  16. 16.
    J. Harden, B. Mbanga, N. Éber, K. Fodor-Csorba, S. Sprunt, J.T. Gleeson, A. Jákli, Phys. Rev. Lett. 97, 157802 (2006).-1CrossRefADSGoogle Scholar

Copyright information

© EDP Sciences, Società Italiana di Fisica and Springer-Verlag 2007

Authors and Affiliations

  1. 1.Institut für Experimentelle PhysikOtto-von-Guericke Universität MagdeburgMagdeburgGermany

Personalised recommendations